From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752573Ab0L1IsM (ORCPT ); Tue, 28 Dec 2010 03:48:12 -0500 Received: from mga02.intel.com ([134.134.136.20]:18783 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752169Ab0L1IsJ (ORCPT ); Tue, 28 Dec 2010 03:48:09 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.60,238,1291622400"; d="scan'208";a="587729893" Subject: Re: [PATCH] apic: use GFP_ATOMIC in lapic_resume From: Zhang Rui To: David Rientjes Cc: "H. Peter Anvin" , LKML , "Rafael J. Wysocki" In-Reply-To: <1293522983.14005.624.camel@rui> References: <1293518922.14005.601.camel@rui> <1293520922.14005.616.camel@rui> <1293522983.14005.624.camel@rui> Content-Type: text/plain; charset="UTF-8" Date: Tue, 28 Dec 2010 16:48:22 +0800 Message-ID: <1293526102.14005.632.camel@rui> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-12-28 at 15:56 +0800, Zhang Rui wrote: > On Tue, 2010-12-28 at 15:39 +0800, David Rientjes wrote: > > On Tue, 28 Dec 2010, Zhang Rui wrote: > > > > > > > Index: linux-2.6/arch/x86/kernel/apic/apic.c > > > > > =================================================================== > > > > > --- linux-2.6.orig/arch/x86/kernel/apic/apic.c > > > > > +++ linux-2.6/arch/x86/kernel/apic/apic.c > > > > > @@ -1459,7 +1459,7 @@ void __init enable_IR_x2apic(void) > > > > > if (dmar_table_init_ret && !x2apic_supported()) > > > > > return; > > > > > > > > > > - ioapic_entries = alloc_ioapic_entries(); > > > > > + ioapic_entries = alloc_ioapic_entries(GFP_KERNEL); > > > > > if (!ioapic_entries) { > > > > > pr_err("Allocate ioapic_entries failed\n"); > > > > > goto out; > > > > > @@ -2084,7 +2084,7 @@ static int lapic_resume(struct sys_devic > > > > > > > > > > local_irq_save(flags); > > > > > if (intr_remapping_enabled) { > > > > > - ioapic_entries = alloc_ioapic_entries(); > > > > > + ioapic_entries = alloc_ioapic_entries(GFP_ATOMIC); > > > > > if (!ioapic_entries) { > > > > > WARN(1, "Alloc ioapic_entries in lapic resume failed."); > > > > > ret = -ENOMEM; > > > > > > > > You can't do the allocation before disabling irqs when > > > > intr_remapping_enabled is set? > > > > > > yes, we can. The first idea came into my mind is to register a pm > > > notifier callback to allocate/free the memory. But that one duplicates > > > the code of alloc_ioapic_entries, which doesn't look nice, neither. > > > Plus, is there any problem with this one? > > > > > > > We try to avoid GFP_ATOMIC whenever possible and this seems like a > > particularly trivial case. You can simply move the alloc_ioapic_entries() > > and NULL check before local_irq_save() and GFP_KERNEL will work fine. > > I'm afraid not. > lapic_resume is invoked in sysdev_resume, which is done with irq > disabled, please refer to the code in kernel/power/suspend.c. > > arch_suspend_disable_irqs(); > BUG_ON(!irqs_disabled()); > > error = sysdev_suspend(PMSG_SUSPEND); > if (!error) { > if (!suspend_test(TEST_CORE) && > pm_check_wakeup_events()) { > error = suspend_ops->enter(state); > events_check_enabled = false; > } > sysdev_resume(); > } > > arch_suspend_enable_irqs(); > BUG_ON(irqs_disabled()); > > To pre-allocate the memory, we need to build a notifier bloack and call > register_pm_notifier. what about this one? Note that it just builds okay, I have not test the patch yet. pre-allocate the memory used in lapic_resume because lapic_resume, as a sysdev .resume callback, is always invoked with irq disabled. Without this patch, I got the following warning messages after resume. [ 109.780371] BUG: sleeping function called from invalid context at mm/slub.c:793 [ 109.780782] in_atomic(): 0, irqs_disabled(): 1, pid: 1391, name: bash [ 109.781024] Pid: 1391, comm: bash Not tainted 2.6.37-rc5+ #182 [ 109.781264] Call Trace: [ 109.781501] [] __might_sleep+0xeb/0xf0 [ 109.781743] [] slab_pre_alloc_hook.clone.33 +0x28/0x31 [ 109.781987] [] __kmalloc+0x88/0x115 [ 109.782224] [] ? kzalloc.clone.19+0x13/0x15 [ 109.782465] [] kzalloc.clone.19+0x13/0x15 [ 109.782704] [] alloc_ioapic_entries+0x20/0x82 [ 109.782948] [] lapic_resume+0x3a/0x245 [ 109.783189] [] ? cpufreq_resume+0x30/0xb0 [ 109.783431] [] __sysdev_resume+0x25/0xc5 [ 109.783673] [] sysdev_resume+0xb6/0xfb [ 109.783914] [] suspend_devices_and_enter +0x13c/0x1c1 [ 109.784159] [] enter_state+0xdd/0x12e [ 109.784398] [] state_store+0xae/0xcb [ 109.784640] [] kobj_attr_store+0x17/0x19 [ 109.784882] [] sysfs_write_file+0x114/0x150 [ 109.785124] [] vfs_write+0xac/0xff [ 109.785365] [] sys_write+0x4a/0x6e [ 109.785604] [] system_call_fastpath+0x16/0x1b Signed-off-by: Zhang Rui --- arch/x86/kernel/apic/apic.c | 38 +++++++++++++++++++++++++++++++++----- 1 file changed, 33 insertions(+), 5 deletions(-) Index: linux-2.6/arch/x86/kernel/apic/apic.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/apic/apic.c +++ linux-2.6/arch/x86/kernel/apic/apic.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include @@ -2033,6 +2034,34 @@ static struct { unsigned int apic_thmr; } apic_pm_state; +static struct IO_APIC_route_entry **ioapic_entries; + +static int lapic_notifier_cb(struct notifier_block *nb, + unsigned long val, void *unused) +{ + switch(val) { + case PM_HIBERNATION_PREPARE: + case PM_SUSPEND_PREPARE: + case PM_RESTORE_PREPARE: + ioapic_entries = alloc_ioapic_entries(); + if (!ioapic_entries) + return NOTIFY_BAD; + return NOTIFY_OK; + case PM_POST_HIBERNATION: + case PM_POST_SUSPEND: + case PM_POST_RESTORE: + free_ioapic_entries(ioapic_entries); + ioapic_entries = NULL; + return NOTIFY_OK; + } + return NOTIFY_BAD; +} + +static struct notifier_block lapic_pm_nb = { + .notifier_call = lapic_notifier_cb, + .priority = 0, +}; + static int lapic_suspend(struct sys_device *dev, pm_message_t state) { unsigned long flags; @@ -2077,14 +2106,12 @@ static int lapic_resume(struct sys_devic unsigned long flags; int maxlvt; int ret = 0; - struct IO_APIC_route_entry **ioapic_entries = NULL; if (!apic_pm_state.active) return 0; local_irq_save(flags); if (intr_remapping_enabled) { - ioapic_entries = alloc_ioapic_entries(); if (!ioapic_entries) { WARN(1, "Alloc ioapic_entries in lapic resume failed."); ret = -ENOMEM; @@ -2094,7 +2121,6 @@ static int lapic_resume(struct sys_devic ret = save_IO_APIC_setup(ioapic_entries); if (ret) { WARN(1, "Saving IO-APIC state failed: %d\n", ret); - free_ioapic_entries(ioapic_entries); goto restore; } @@ -2145,7 +2171,6 @@ static int lapic_resume(struct sys_devic reenable_intr_remapping(x2apic_mode); legacy_pic->restore_mask(); restore_IO_APIC_setup(ioapic_entries); - free_ioapic_entries(ioapic_entries); } restore: local_irq_restore(flags); @@ -2183,8 +2208,11 @@ static int __init init_lapic_sysfs(void) /* XXX: remove suspend/resume procs if !apic_pm_state.active? */ error = sysdev_class_register(&lapic_sysclass); - if (!error) + if (!error) { error = sysdev_register(&device_lapic); + if (!error) + error = register_pm_notifier(&lapic_pm_nb); + } return error; }